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Old October 27, 2012, 12:14 PM   #14
Join Date: March 4, 2005
Location: Ohio
Posts: 13,720
Probably some terminology should be defined. There are four kinds of uniforming that are commonly done to primer pockets. Depth uniforming, profile uniforming, flash hole uniforming, and flash hole deburring. Depth uniforming is done with a carbide end cutter like the one mentioned and linked to earlier. Profile uniforming is done with a swager or with a primer pocket reamer. In the process any sort of crimp is also removed.

If you want to remove the crimp, but don't care about profile uniforming, then I think the chamfer tools are adequate. If you want to uniform the primer pocket profile, it does make primer seating feel more consistent, and in the case of harder to seat primers, like the Russian KVB primers, it definitely makes that less of a chore.

If you want to uniform pocket depth, it is usually done both to improve ignition consistency and to reduce slamfire probability in gas guns. It gets more important in high reload count cases, as the brass at the bottom of the primer pocket tends to flow rearward over timer, making it shallower. Many now use the depth uniforming tools to clean primer pocket residue because it tends to trim flowed brass down at the same time.

Uniforming flash holes is a waste of time if you don't deburr them. This is really a benchrest precision step. Hole chucking reamers are available for the purpose. Deburring flash holes is something I've found to make a measurable improvement with some spherical propellants, but seldom see a difference with stick powders. Both are ignition consistency improving techniques, so the harder the powder you have is to light, the more you should consider trying them to see if you get an improved group size.
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